Human tyrosinase is an essential enzyme which regulates the production of melanin, a group of brown or black pigments in the skin and eyes of humans. The lack of a human tyrosinase gene in usable form has greatly limited medical research in the field of albinism, and other medical and nonmedical applications relating to the control of pigment production in human melanocyte cells. This invention relates to the discovery of the cDNA gene which expresses human tyrosinase. When the cDNA is fused to an expression vector, the cDNA is useful to produce pure tyrosinase. When used as a cDNA probe the DNA is useful in the production or the control of production of human melanin. As a cDNA probe the cDNA gene is useful for genetic analysis of human albinism and melanotic and amelanotic melanoma, and also prenatal diagnosis of albinism.
There has been a minimum of research on the genetic control of melanin formation because of the lack of availability of suitable nucleic acid probe (gene sequence). cDNA for human tyrosinase is a key material for the study. The material will serve to understand why some melanoma cells lose the expression of tyrosinase gene and become more invasive. Differences in tyrosinase expression in cancer cells make it possible that the gene probe can be used in understanding and as a marker for malignancy. Understanding of the regulation of melanin biosynthesis will lead to the development of a rational chemotherapy of human melanoma because the intermediate substances of melanin are known to be toxic to pigment cells. Deletion of genes around albino locus (tyrosinase structural gene) becomes lethal in mice. The cDNA probe will open up a new research area to identify genes causing lethal effect in mouse embryo.